Fix duplicate keyper set error

On startup, the chainsyncer gives all keyper sets it can find in the
keyper set manager to its subscribers, no matter if they are actually
new or already in the db. This results in duplicate primary key errors
when we try to insert them a second time.

To fix this, the SQL query now does not insert the keyper set if it is
already present.

Author: jannikluhn

rolling-shutter/chainobserver/db/keyper/keyper.sqlc.gen.go

@@ -6,7 +6,7 @@ INSERT INTO keyper_set (
     threshold
 ) VALUES (
     $1, $2, $3, $4
-);
+) ON CONFLICT DO NOTHING;
 
 -- name: GetKeyperSetByKeyperConfigIndex :one
 SELECT * FROM keyper_set WHERE keyper_config_index=$1;